FLIG AND FLIM DISTRIBUTION IN THE SALMONELLA-TYPHIMURIUM CELL AND FLAGELLAR BASAL BODIES

Salmonella typhimurium FliG and FliM are two of three proteins known t o he necessary for flagellar morphogenesis as well as energization and switching of flagellar rotation, We have determined FliC and FliM lev els in cellular fractions and in extended flagellar basal bodies, usin g antibodies raised against the purified proteins. Both proteins were found predominantly in the detergent-solubilized particulate fraction containing flagellar structures, Basal flagellar fragments could be se parated from partially constructed basal bodies by gel filtration chro matography. FliG and FliM were present in an approximately equimolar r atio in all gel-filtered fractions, FliG and FliM copy numbers, estima ted relative to that of the hook protein from the early fractions cont aining long, basal, flagellar fragments, were (means +/- standard erro rs) 41 +/- 10 and 37 +/- 13 per flagellum, respectively, Extended stru ctures were present in the earliest identifiable basal bodies, Immunoe lectron microscopy and immunoblot gel analysis suggested that the FliG and, to a less certain degree, the FliM contents of these structures were the same as those for the complete basal bodies. These facts are consistent with the postulate that FliG and FliM affect flagellar morp hogenesis as part of the extended basal structure, formation of which is necessary for assembly of more-distal components of the flagellum, The determined stoichiometries will provide important constraints to m odelling energization and switching of flagellar rotation.